An ESP system (electronic stability program) relates to the control of the vehicle behavior in the physical driving limits and is to influence the three degrees of freedom of the vehicle in the plane of the road (linear and lateral velocities and yaw velocity about the vertical axis) so that the vehicle handling is adapted to the driver command and the prevailing road surface conditions. In this respect it must first be determined how the vehicle is to behave (nominal behavior) in accordance with the driver command and how it actually behaves (actual behavior). In order to minimize the difference between nominal and actual behavior (system deviation), the tire forces must in some way be controlled by actuators.
The overall system shows the vehicle as controlled system, with sensors for defining the controller input variables, actuators for influencing the braking and motive forces, as well as the hierarchically structured controller, made up of the higher-level vehicle dynamics controller and lower-level slip controllers. The higher-level controller defines nominal values for the lower-level controller in the form of nominal slip. The “observer” determines the controlled state variable.
In order to determine the nominal behavior, the signals describing the driver's command of the steering-wheel angle sensor (desired steering), of the brake-pressure sensor (desired deceleration), and of the engine management (desired drive torque) are evaluated. In addition, the calculation of the nominal behavior also takes the vehicle speed into account, which is estimated from the signals of the wheel-speed sensors, the lateral-acceleration sensor, the yaw-rate sensor and the brake-pressure sensor. Depending on the system deviation, the yaw moment required to make the actual-state variables approach the nominal state variables is calculated.
In order to generate this nominal yaw moment, the vehicle dynamics controller determines the necessary changes in the nominal slip at the appropriate wheels. These are adjusted by the lower brake- and the drive-slip controllers together with the brake and engine actuators. Such an ESP system relies on known ABS and TCS components. The engine control unit having a CAN interface is able to set the required engine torque and thus the drive slip values at the wheels.
A generic device is disclosed in EP 0 922 618 B1. There, the yaw rate sensor and the transverse acceleration sensor are integrated in the electronic driving dynamics system. This results in certain advantages with regard to savings in connection with the wiring and housings.
In contrast, the exemplary embodiments and/or exemplary methods of the present invention is based on the objective of further developing a device of the type mentioned at the outset, to the effect that the integration degree is increased and specific advantages are obtained simultaneously as a result.
According to the exemplary embodiments and/or exemplary methods of the present invention, this objective is achieved by the features described herein.